The illumination of roadways, parking lots, outdoor sports facilities, and the like, is typically accomplished by means of directed light sources suspended at the top of tall poles. For example, light poles are commonly found uniformly positioned along city streets and highways.
A light pole typically includes a light source suspended at the top of a tall pole, typically 15 to 18 meters above the ground. A light is typically encased in a fixture having reflective and/or refractive portions used to direct the light to the ground below in a desired pattern. The fixture may also include a transformer or ballast, wiring, and other components necessary to provide a bright directed source of light at the top of a pole. The light and fixture typically are very heavy. Accordingly, to suspend the light and the light fixture, a heavy pole, typically made of a heavy gauge metal, is required.
Light poles are positioned at uniform intervals, for example, along a highway or other roadway. The brightness of the light source, the characteristics of the reflectors and/or refractors contained in the fixture, the height that the light source is positioned above the ground, and the distance between adjacent light poles, all contribute to the intensity and pattern of the light illuminating the ground or other surface surrounding the pole. The uniformity of the light illuminating the ground is quantified by the ratio of illumination, defined as the ratio between the brightest spot and the darkest spot. A 7:1 ratio of illumination is considered fairly uniform, while ratios of 100-1000:1 are not uncommon. A ratio of illumination of less than 3:1 would be highly desirable.
Standard light poles, having a directed light source suspended a the ground, present problems involving cost, maintenance, and safety. Because of the materials required to suspend the heavy light and fixture above the ground, the cost of such light poles can be significant. Maintenance of such light poles is also costly and time consuming. To change a light bulb in a suspended light fixture, it is necessary to use a lifting device, such as a telescoping man lift or hoist, attached to a highway maintenance vehicle. In addition to the cost of the two or three persons necessary to operate the lift truck, the presence of such a vehicle on the side of a roadway can be dangerous, both to the maintenance personnel and to the motorist. The presence of the poles themselves along a roadway also presents the danger of the pole being struck by a motorist. Because such poles are typically heavy gauge metal, the impact with such a pole can have severe consequences. In addition, the heavy light fixture and the heavy metal pole, present a significant danger in falling subsequent to impact by a vehicle.
In a different technical field, light conduits capable of transmitting large quantities of light energy from one place to another are known. Such light transmitting conduits are useful in a wide variety of applications, for example, in transmitting sunlight from outdoors into the interior of a room. Such light conduits typically operate on the principle of total internal reflection, having a plurality of 45.degree. angle prisms extending the length of the conduit to totally internally reflect the light as it travels along the length of the conduit. See, for example, U.S. Pat. Nos. 4,260,220; 4,805,984; 4,750,789; and 4,615,579.
In view of the disadvantages inherent in the presently known light poles, there is a need for an apparatus that transports light from a light source that can be located at or near ground level upward to a reflecting member, that distributes the light uniformly to the ground below. There is also a need for a reflective sheeting material that may, for example, be provided in a reflection chamber adapted to be provided at the top of a light conduit to reflect an area source of light emitted from the light conduit in a broad, uniformly distributed pattern.